System for liquid separation

Abstract

A rotor for collecting and centrifuging biological fluids in a range of volumes. The rotor includes an elastic impermeable diaphragm which defines at least a portion of a variable-volume processing chamber, where the fluid is centrifuged. The rotor includes a rigid mounting member, to which the diaphragm is mounted and which is held and spun by a chuck. Preferably, this rigid mounting member includes a boundary wall which together with the elastic diaphragm defines the chamber. The boundary wall may be a substantially imperforate circular wall which extends to the periphery of the processing chamber but defining one opening, preferably near the axis of rotation, permitting a conduit or conduits to pass therethrough so as to be in fluid communication with the processing chamber. The rotor may include a separate structure for controlling the flow of liquid out of the chamber into the conduit. In a preferred embodiment, this outlet-control structure is a perforate, substantially rigid wall or plate, located within the processing chamber and mounted adjacent the rigid boundary wall. In an alternative embodiment, the outlet-control structure for controlling flow from the processing chamber to the conduit may include at least one tube or preferably a set of tubes, wherein each tube provides fluid communication between the chamber and the conduit. In one preferred embodiment, grooves in the boundary wall may be used as the outlet-control structure.

What is claimed is: 
     
       1. A centrifuge system for accepting a rotor having a rigid mounting member and an elastic diaphragm attached to the mounting member, the system comprising: means for holding the rigid mounting member of the rotor and for spinning the rotor around an axis; and   means for changing the pressure of a control fluid adjacent the rotor's diaphragm.   
     
     
       2. A centrifuge system according to 1, wherein the control fluid in the pressure-changing means is a gas. 
     
     
       3. A system according to claim 2, wherein the spinning means includes a chuck and the pressure-changing means is in fluid communication with the chuck. 
     
     
       4. A system according to claim 2, wherein the pressure-changing means includes means for applying a vacuum against the diaphragm, so as to draw fluid into the rotor. 
     
     
       5. A system according to claim 1, wherein the pressure-changing means includes means for applying pressurized gas against the diaphragm, so as to force fluid out of the rotor. 
     
     
       6. A system according to claim 5, wherein the pressure-changing means further includes means for applying a vacuum against the diaphragm, so as to draw fluid into the rotor. 
     
     
       7. A system according to claim 5, wherein the pressure against the diaphragm is held constant while the speed the spinning means spins the rotor is reduced, so as to force fluid out of the rotor. 
     
     
       8. A system according to claim 5, wherein the pressure against the diaphragm is increased while the speed the spinning means spins the rotor is reduced, so as to force fluid out of the rotor. 
     
     
       9. A system according to claim 5, wherein the pressure against the diaphragm is increased while the speed the spinning means spins the rotor is kept constant, so as to force fluid out of the rotor. 
     
     
       10. A system according to claim 5, further including control means for controlling the speed of rotation of the spinning means, and for controlling the pressure-changing means. 
     
     
       11. A system according to claim 10, wherein the control means causes fluid to be forced out of the rotor by reducing the speed of the spinning means and the rotor. 
     
     
       12. A system according to claim 11, wherein the control means causes the spinning means to spin at a constant speed, while the pressure-changing means increases the pressure against the diaphragm, until a predetermined pressure is reached, then causes the pressure changing means to maintain a constant pressure against the diaphragm, while reducing the speed of the spinning means. 
     
     
       13. A system according to claim 11, wherein the control means causes the pressure-changing means to maintain a constant pressure against the diaphragm, while causing the rotor to reduce its speed of spinning until a predetermined speed is reached, then causes the pressure-changing means to increase the pressure against the diaphragm. 
     
     
       14. A system according to claim 10, wherein the control means includes means for determining the volume of fluid in the rotor based on the speed of the spinning means and the pressure created by the pressure-changing means. 
     
     
       15. A system according to claim 14, wherein the control means includes means for controlling the volume of fluid in the rotor by controlling the speed of the spinning means and the pressure created by the pressure-changing means. 
     
     
       16. A system according to claim 15, wherein the control means causes the volume of the processing chamber to remain constant. 
     
     
       17. A system according to claim 15, wherein the control means includes means for causing the rotor to stop at some point and causing the pressure-changing means to force the remaining fluid out of the rotor. 
     
     
       18. A centrifuge system for accepting a rotor having an elastic diaphragm defining a variable-volume chamber, the system comprising: means for spinning the rotor around an axis; and   means for changing the pressure of a gas adjacent the rotor's diaphragm, so as provide a vacuum for drawing fluid into the chamber and so as to provide pressurized gas for forcing fluid out of the chamber.   
     
     
       19. A system according to claim 18, wherein the pressure against the diaphragm is held constant while the speed the spinning means spins the rotor is reduced, so as to force fluid out of the rotor. 
     
     
       20. A system according to claim 18, wherein the pressure against the diaphragm is increased while the speed the spinning means spins the rotor is kept constant, so as to force fluid out of the rotor. 
     
     
       21. A system according to claim 18, wherein the pressure against the diaphragm is increased while the speed the spinning means spins the rotor is reduced, so as to force fluid out of the rotor. 
     
     
       22. A system according to claim 18, further including control means for controlling the speed of rotation of the spinning means and the rotor, and for controlling the pressure-changing means. 
     
     
       23. A system according to claim 22, wherein the control means causes fluid to be forced out of the rotor by reducing the speed of the spinning means and the rotor. 
     
     
       24. A system according to claim 23, wherein the control means causes the rotor to spin at a constant speed, while the pressure-changing means increases the pressure against the diaphragm, until a predetermined pressure is reached, then reduces the speed of the spinning means and rotor. 
     
     
       25. A system according to claim 22, wherein the control means causes the pressure-changing means to maintain a constant pressure against the diaphragm, while causing the rotor to reduce its speed of spinning until a predetermined speed is reached, then causes the pressure-changing means to increase the pressure against the diaphragm. 
     
     
       26. A system according to claim 22, wherein the control means includes means for determining the chamber's volume based on the speed of the spinning means and the pressure created by the pressure-changing means. 
     
     
       27. A system according to claim 26, wherein the control means includes means for controlling the volume of fluid in the rotor by controlling the speed of the spinning means and the pressure created by the pressure-changing means. 
     
     
       28. A centrifuge system for accepting a rotor, the system comprising: means for spinning the rotor around an axis; and   control means for controlling the spinning means so as to cause the spinning means to continually cycle through a range of rotational speeds around a desired rotational speed, so as to prevent the system from vibrating excessively.   
     
     
       29. A centrifuge system for accepting a rotor having a rigid mounting member and an elastic diaphragm attached to the mounting member, the system comprising: a chuck capable of holding the rigid mounting member of the rotor and spinning the rotor around an axis; and   a pump for changing the pressure of a control fluid adjacent the rotor's diaphragm.   
     
     
       30. A centrifuge system for accepting a rotor having an elastic diaphragm defining a variable-volume chamber, the system comprising: a chuck that spins the rotor around an axis; and   a pump that changes the pressure of a gas adjacent the rotor's diaphragm, so as provide a vacuum for drawing fluid into the chamber and so as to provide pressurized gas for forcing fluid out of the chamber.   
     
     
       31. A centrifuge system for accepting a rotor, the system comprising: a chuck that spins the rotor around an axis; and   a controller that causes the chuck to continually cycle through a range of rotational speeds around a desired rotational speed, so as to prevent the system from vibrating excessively.